Selecting hardware for general industrial applications typically follows a familiar pattern: identify the fastener type, choose a material, and then choose a spec or grade. Here, the material selection step indirectly addresses any minor environmental concerns, such as exposure to sunlight, rain, or sea water. In certain applications however, we have to fully consider the fastener’s environment as the first decision point in the selection process, and Washdown Environments are a perfect example of such an application.
Here we’ll begin a two-part article series on selecting fasteners for washdown environments.
Washdown environments are typically found in Food, Beverage, Pharmaceutical, and other hygienic manufacturing facilities. The term “washdown” refers to the expectation that hot cleaning water and chemicals will be employed to rinse, sanitize, disinfect, or sterilize every inch of a given space, including all equipment installed within that space. Due to the exposure of all hardware used within such space to hot water and strong chemicals, we start our fastener selection process considering multiple unique requirements, such as:
- Resistant and stable at high temperatures, typically 145F to 185F
- Resistant to high pressures, typically 2,500 to 5,000 PSI where pressure washing is used
- Corrosion-proof under exposure to caustic, acid, and chlorine cleaning chemicals
- Inert in terms of carryover into food products (example: not using carbon materials where rust can be carried into product-contact areas)
- Free of harborage features, such as pockets that can retain soil particles and are not freely draining of water, resulting in bacterial growth
- Water-tight sealing capability, such as where fasteners are used to seal off machine service panels from outside cleaning
- Certified or conforming to applicable codes depending on the industry and country of use, such as 3A, EHEDG, ISO 9001, USDA, FDA, and cGMPs.
E&T Fasteners provides high stock volumes of the most common fasteners used in washdown environments, spanning both corrosion-proof metallic and plastic materials. See more about our fastener offerings here.
All of the many unique requirements mentioned above can seem overwhelming at first, but there is good news coming up next! Today, we benefit from decades of collaboration between hygienic industries and regulatory bodies, whose work has long since established a short-list of options for washdown materials. Effectively, most of the time we’ll only need to choose between Stainless Steel Type 304 and Type 316.
The Stainless Steel metal family is the preferred choice for washdown materials. With compositions that include chromium and nickel, these metals have the best combination of features matching our above requirements and price. Stainless materials are naturally corrosion-resistant, temperature stable, and chemical-resistant for low to moderate chemical concentrations.
- Stainless Steel Type 304 – the most common selection for washdown environments, consisting of 18% chromium and 8% nickel, this material is best for all non-product contact, medium-duration washdown exposure. Also known as Stainless Steel 18-8 for fasteners.
- Stainless Steel Type 316 – the second-most common selection for washdown environments, consisting of 18% chromium and 10% nickel, this material is best for direct food-contact, high-duration, or high-chemical concentration washdown exposure. Also known as Stainless Steel 18-10 for fasteners.
Other materials for washdown fasteners do exist, however such alternatives are typically either cost-prohibitive, require ongoing maintenance such as re-coating, or have significantly lower performance in some aspect of washdown functionality. A few examples:
- Titanium is highly acid-resistant and extremely durable to wear, but is very expensive and not widely available
- Aluminum does not rust, is acceptable to ambient-temperature water exposure, and is low-cost, but is highly susceptible to chemical corrosion, and has low strength
- Multiple plastics such as PTFE, PEEK, UHMW, and more are all corrosion resistant, low cost, and non-toxic, however may not stand up to chemical attack, high pressures, or high temperatures
- In rare cases, other materials such as high-strength steel fasteners are used on special equipment, requiring that they are coated with an epoxy or similar sealant to withstand washdown exposure. These applications require that the coating or sealant is inspected and maintained constantly, as any breach of the sealant could expose the fastener and lead to failure
Our sales representatives are experienced in Food, Beverage, and Hygienic Washdown Environments, and can assist you in selecting the ideal material for your project. Speak with an E&T sales representative for assistance comparing costs and benefits for these special applications.
Part Two – Coming Next!
In our next article, we’ll continue the discussion on Washdown Environment fasteners by covering various surface finish and feature considerations, as well as providing examples of how to select alternative fasteners to promote washdown performance. Stay tuned, and thanks for reading!
About E&T Fasteners
With sales and support teams spanning the Continental US, E&T Fasteners is here to serve your hardware, fastening, and component needs both domestically and internationally. We are a stocking distributor of metallic, plastic, and exotic alloy fasteners, backed by our technical staff directly experienced in your unique applications. We can assist your specifying and selection efforts, providing engineered solutions, record-fast lead times, and stellar customer service from quote through delivery. Please let us know how we can help!